1. Field of the Invention
The present invention relates to an optical receiver, in particular, the invention relates to an optical receiver than may compensate an input offset.
2. Background
A differential trans-impedance amplifier (hereafter denoted as TIA) with an offset canceller has been known in the field. A Japanese Patent Application published as JP-2003-168933A has discloses a differential circuit to suppress an input offset by detecting an output offset and feeding the detected offset back to an inter stage of the amplifier to cancel the output offset.
Another Japanese Patent Application published as JP-2003-264437A has disclosed an optical receiver to cancel an output offset of a front end amplifier by detecting peak signal input therein. A Japanese Patent Application published as 2010-278753A has disclosed a differential amplifier that detects an input offset through an average thereof, and extracts a current corresponding to the input offset from a current flowing in the output load to cancel the output offset. Still another Japanese Patent Application published as JP-H07-240640 has disclosed another differential amplifier to balance the input bias current by filtering the outputs of the amplifier.